EP2610325A1

EP2610325A1 - A process for the preparation of detergent compounds

Info

Publication number: EP2610325A1
Application number: EP11196153.8A
Authority: EP
Inventors: Eduard Philip Kieffer; Duurt Renkema; Jelle Rudolf Anne Sietsma
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2011-12-30
Filing date: 2011-12-30
Publication date: 2013-07-03

Abstract

The invention concerns a process for the preparation of detergents comprising separating by distillation a Fischer-Tropsch product into a light fraction (A), a first intermediate fraction (Bⁱ) comprising at least 80 wt% C₁₀ to C₁₄ hydrocarbons, a second intermediate fraction (Bⁱⁱ) comprising at least 80 wt% C₁₄ to C₁₈ hydrocarbons, and a heavy fraction (C). The fractions (Bⁱ) and (Bⁱⁱ) are hydrogenated. The hydrogenated first intermediate fraction is distilled into a fraction (Bⁱ¹) comprising at least 80 wt% C₁₀ to C₁₃ hydrocarbons and a fraction (Bⁱ²) comprising at least 80 wt% C₁₄ hydrocarbons. The hydrogenated second intermediate fraction is distilled into a fraction (Bⁱⁱ¹) comprising at least 80 wt% C₁₄ to C₁₇ hydrocarbons and a fraction (Bⁱⁱ²) comprising at least 80 wt% C₁₈ hydrocarbons. The C₁₀ to C₁₃ hydrocarbons and/or the C₁₄ to C₁₇ hydrocarbons are converted into detergents.

Description

The present invention relates to a process for the preparation of detergents with a relatively low amount of isoparaffins, wherein the detergents are derived from a Fischer-Tropsch product stream.
The Fischer-Tropsch process is well known in the art. Synthesis gas, a mixture of hydrogen and carbon monoxide, is converted over a catalyst usually comprising a Group VIII metal or metal compound at elevated temperature and usually elevated pressure into mainly paraffinic and/or olefinic hydrocarbons and water. Depending on the reaction conditions (temperature, pressure, catalyst, H₂/CO ratio, GHSV etc.) the product properties (e.g. the C₅ ⁺ selectivity, the olefin content, the oxygenate content etc.) may vary. At the present moment there is a clear interest in the use of cobalt based catalyst at a temperature between 180 and 270 °C to make mainly very heavy paraffins comprising a major amount of normally solid hydrocarbons. In such Fischer-Tropsch processes substantial amounts of detergent hydrocarbons are produced, i.e. compounds having suitably 9 to 18 carbon atoms, preferably 10 to 17 carbon atoms.
The preparation of detergents, especially biodegradable detergents, from linear olefins prepared in a Fischer-Tropsch process has been described in the literature. For instance, in ACS Symp. Series No. 238, 18-33 (191 ACS Nat. Meeting Div. Pet. Chem. Symp. New York, 13-18 April 1986) it has been described that C₉-C₁₅ cuts of low and high temperature Fischer-Tropsch processes are suitable feedstocks in the alkylation of benzene to prepare alkylbenzenes, followed by sulfonation and neutralization to convert the alkylbenzenes into alkylbenzene-sulphonates. The direct products of these Fischer-Tropsch processes, using iron based catalysts, comprise rather large amounts of olefins. For instance, the high temperature process results in a product comprising about 70% olefins (60% straight chain product), the low temperature process results in about 25% olefins (linearity 93%). Also US 3,674,885 describes the use of paraffin-olefin mixtures synthesized in a Fischer-Tropsch process in the alkylation of benzene. The paraffins are separated from the alkylation mixture and are recycled to a chlorination unit from which the paraffin-chloroparaffin effluent mixture is combined with the fresh Fischer-Tropsch olefin-paraffin mixture and the combined feeds are used to alkylate the benzene. Detergents may also be made directly from paraffins as described in WO 99/59942 .
There is a preference for linear hydrocarbons for the preparation of detergents. See for instance US 6,392,109 column 1, lines 12 and 13, and lines 28 to 31, where it is indicated that linear detergent hydrocarbon are preferred over branched detergent hydrocarbons. Therefore, there is a desire to prepare detergent hydrocarbons with a (very) low amount of branched hydrocarbons. It has been described in W02004/074407 that when carrying out a Fischer-Tropsch reaction using a cobalt based catalyst the amount of branched hydrocarbons decreases at higher pressures. Thus, when using the same reaction temperature, at higher pressures less branching occurs, at lower pressure more branching occurs.
There is a need for optimised processes for the production of detergents with a relatively low amount of isoparaffins.
The present invention relates to a process for the preparation of detergents containing a relatively low amount of isoparaffins, comprising:

separating by distillation the hydrocarbonaceous product stream from a Fischer-Tropsch process carried out using a cobalt based catalyst and a pressure above 25 bara into
- a light fraction (A) boiling below an intermediate fraction (B),
- an intermediate boiling fraction (B) comprising at least 80 wt% C₁₀ to C₁₇ hydrocarbons based on the total intermediate fraction and
- a heavy fraction (C) boiling above the intermediate boiling fraction (B),
hydrogenating the intermediate boiling fraction (B),
separating the hydrogenated intermediate boiling fraction by distillation into
- a fraction (B^I) comprising at least 80 wt% C₁₀ to C₁₃ hydrocarbons based on the total fraction (B^I) and
- a fraction (B^II) comprising at least 80 wt% C₁₄ to C₁₇ hydrocarbons based on the total fraction (B^II) and
converting the C₁₀ to C₁₃ hydrocarbons in the fraction (B^I) into detergents and/or converting the C₁₄ to C₁₇ hydrocarbons in the fraction (B^II) into detergents.

The present invention further relates to a process for the preparation of detergents containing a relatively low amount of isoparaffins, comprising:

separating by distillation the hydrocarbonaceous product stream from a Fischer-Tropsch process carried out using a cobalt based catalyst and a pressure above 25 bara into
- a light fraction (A) boiling below an intermediate fraction (B),
- an intermediate boiling fraction (B) comprising at least 80 wt% C₁₀ to C₁₄ hydrocarbons based on the total intermediate fraction and
- a heavy fraction (C) boiling above the intermediate boiling fraction (B),
hydrogenating the intermediate boiling fraction (B),
separating the hydrogenated intermediate boiling fraction by distillation into
- a fraction (B¹) comprising at least 80 wt% C₁₀ to C₁₃ hydrocarbons based on the total fraction (B¹) and
- a fraction (B²) comprising at least 80 wt% C₁₄ hydrocarbons based on the total fraction (B²),
converting the C₁₀ to C₁₃ hydrocarbons in the fraction (B¹) into detergents, and
optionally subjecting the fraction (B²) to hydrocracking.

The present invention also relates to a process for the preparation of detergents containing a relatively low amount of isoparaffins, comprising:

separating by distillation the hydrocarbonaceous product stream from a Fischer-Tropsch process carried out using a cobalt based catalyst and a pressure above 25 bara into
- a light fraction (A) boiling below a first intermediate fraction (Bⁱ),
- a first intermediate fraction (Bⁱ) comprising at least 80 wt% C₁₀ to C₁₄ hydrocarbons based on the total first intermediate fraction (Bⁱ),
- a second intermediate fraction (Bⁱⁱ) comprising at least 80 wt% C₁₄ to C₁₈ hydrocarbons based on the total second intermediate fraction (Bⁱⁱ), and
- a heavy fraction (C) boiling above the second intermediate fraction (Bⁱⁱ),
hydrogenating the fraction (Bⁱ) and hydrogenating the fraction (Bⁱⁱ),
separating the hydrogenated first intermediate fraction by distillation into
- a fraction (Bⁱ¹) comprising at least 80 wt% C₁₀ to C₁₃ hydrocarbons based on the total fraction (Bⁱ¹)
- a fraction (Bⁱ²) comprising at least 80 wt% C₁₄ hydrocarbons based on the total fraction (Bⁱ²),
separating the hydrogenated second intermediate fraction by distillation into
- a fraction (Bⁱⁱ¹) comprising at least 80 wt% C₁₄ to C₁₇ hydrocarbons based on the total fraction (Bⁱⁱ¹) and
- a fraction (Bⁱⁱ²) comprising at least 80 wt% C₁₈ hydrocarbons based on the total fraction (Bⁱⁱ²)
optionally adding the fraction (Bⁱ²) to the fraction (Bⁱⁱ¹)
converting the C₁₀ to C₁₃ hydrocarbons in the fraction (Bⁱ¹) into detergents, and/or converting the C₁₄ to C₁₇ hydrocarbons in the fraction (Bⁱⁱ¹), or in (Bⁱⁱ¹) plus (Bⁱ²), into detergents, and
optionally subjecting at least a part of the fraction (Bⁱⁱ²) to hydrocracking.

In a preferred embodiment the fraction (Bⁱ²) is added to the fraction (Bⁱⁱ¹).
In a more preferred embodiment the fraction (B¹²) is added to the fraction (Bⁱⁱ¹) and the C₁₄ to C₁₇ hydrocarbons in (Bⁱⁱ¹) plus (Bⁱ²) are converted into detergents.
In an even more preferred embodiment the fraction (Bⁱ²) is added to the fraction (Bⁱⁱ¹), the C₁₀ to C₁₃ hydrocarbons in the fraction (Bⁱ¹) are converted into detergents, and the C₁₄ to C₁₇ hydrocarbons in (Bⁱⁱ¹) plus (Bⁱ²) are converted into detergents. This embodiment is advantageous because it results in a maximum yield of detergents from the fractions (Bⁱ) and (Bⁱⁱ).
The process according to the invention may be carried out at all suitable pressures above 25 bara.
Preferably the Fischer-Tropsch process is carried out at a pressure above 35 bara, more preferably above 45 bara, still more preferably above 55 bara. The higher the pressure during the Fischer-Tropsch process, the less the amount of branched detergent hydrocarbons are obtained. A practical upper limit for the Fischer-Tropsch process is 200 bara, preferably the Fischer-Tropsch process is carried out at a pressure below 120 bara, more preferably below 100 bara. The Fischer-Tropsch process is suitably a low temperature process carried out at a temperature between 170 and 290 °C, preferably at a temperature between 180 and 270 °C, more preferably between 200 and 250 °C. At higher temperature the conversion of synthesis gas into hydrocarbons is higher, however, the degree of branching (or the formation of iso-paraffins) is also higher. The above indicated temperatures, in combination with a pressure above 25 bara, result in a satisfactory syngas conversion, while branching is still at an acceptable (low) level. The amount of isoparaffins is suitably less than 20 wt% based on the total amount of C₁₀ to C₁₈ hydrocarbons, especially less than 10 wt%, preferably less than 7 wt%, more preferably less than 4 wt%. The relatively low amount of isoparaffins relates to a decreased amount of isoparaffins produced at pressures above 25 bara when compared with lower pressures. Suitably this means at least 5 mol % less isoparaffin when compared with a pressure of 20 bara.
In the Fischer-Tropsch process a mixture of hydrogen and carbon monoxide is catalytically converted into hydrocarbons and water. The Fischer-Tropsch catalysts are known in the art. Catalysts for use in this process frequently comprise, as the catalytically active component, a metal from Group VIII of the Periodic Table of Elements. Particular catalytically active metals include ruthenium, iron, cobalt and nickel. Cobalt is the catalytically active metal in the process of the present invention. Preferred hydrocarbonaceous feeds are natural gas or associated gas. These feedstocks usually result in synthesis gas having H₂/CO ratio's of about 2.
The catalytically active metal is preferably supported on a porous carrier. The porous carrier may be selected from any of the suitable refractory metal oxides or silicates or combinations thereof known in the art. Particular examples of preferred porous carriers include silica, alumina, titania, zirconia, ceria, gallia and mixtures thereof, especially silica, alumina and titania.
The amount of catalytically active metal on the carrier is preferably in the range of from 3 to 300 pbw per 100 pbw of carrier material, more preferably from 10 to 80 pbw, especially from 20 to 60 pbw.
If desired, the catalyst may also comprise one or more metals or metal oxides as promoters. Suitable metal oxide promoters may be selected from Groups IIA, IIIB, IVB, VB and VIB of the Periodic Table of Elements, or the actinides and lanthanides. In particular, oxides of magnesium, calcium, strontium, barium, scandium, yttrium, lanthanum, cerium, titanium, zirconium, hafnium, thorium, uranium, vanadium, chromium and manganese are very suitable promoters. Particularly preferred metal oxide promoters for the catalyst used to prepare the waxes for use in the present invention are manganese and zirconium oxide. Suitable metal promoters may be selected from Groups VIIB or VIII of the Periodic Table. Rhenium and Group VIII noble metals are particularly suitable, with platinum and palladium being especially preferred. The amount of promoter present in the catalyst is suitably in the range of from 0.01 to 100 pbw, preferably 0.1 to 40, more preferably 1 to 20 pbw, per 100 pbw of carrier. The most preferred promoters are selected from vanadium, manganese, rhenium, zirconium and platinum.
The catalytically active metal and the promoter, if present, may be deposited on the carrier material by any suitable treatment, such as impregnation, kneading and extrusion. After deposition of the metal and, if appropriate, the promoter on the carrier material, the loaded carrier is typically subjected to calcination. The effect of the calcination treatment is to remove crystal water, to decompose volatile decomposition products and to convert organic and inorganic compounds to their respective oxides. After calcination, the resulting catalyst may be activated by contacting the catalyst with hydrogen or a hydrogen-containing gas, typically at temperatures of about 200 to 350 °C. Other processes for the preparation of Fischer-Tropsch catalysts comprise kneading/mulling, often followed by extrusion, drying/ calcination and activation.
The catalytic conversion process may be performed under conventional synthesis conditions known in the art. Typically, the catalytic conversion may be effected at a temperature and pressure as described above. In the catalytic conversion process especially more than 75 wt% of C₅ ⁺, preferably more than 85 wt% C₅ ⁺ hydrocarbons are formed. Depending on the catalyst and the conversion conditions, the amount of heavy wax (C₂₀ ⁺) may be up to 60 wt%, sometimes up to 70 wt%, and sometimes even up till 85 wt%. Preferably a cobalt catalyst is used, a low H₂/CO ratio is used (especially 1.7, or even lower) and a low temperature is used (200-250 °C), in combination with a high pressure. To avoid any coke formation, it is preferred to use an H₂/CO ratio of at least 0.6. It is especially preferred to carry out the Fischer-Tropsch reaction under such conditions that the ASF-alpha value (Anderson-Schulz-Flory chain growth factor), for the obtained products having at least 20 carbon atoms, is at least 0.925, preferably at least 0.935, more preferably at least 0.945, even more preferably at least 0.955.
A most suitable catalyst for this purpose is a cobalt-containing Fischer-Tropsch catalyst.
Such catalysts are described in the literature, see e.g. AU 698392 and WO 99/34917 .
The Fischer-Tropsch process may be a slurry FT process, an ebullated bed process or a fixed bed FT process, especially a multitubular fixed bed. The product stream of the Fischer-Tropsch process is usually separated into a water stream, a gaseous stream comprising unconverted synthesis gas, carbon dioxide, inert gasses and C₁ to C₃, and optionally C₄, compounds. The full Fischer-Tropsch hydrocarbonaceous product suitably comprises a C₃ to C₂₀₀ fraction, preferably C₄ to C₁₅₀ fraction. The separation into the one or more light fractions, the intermediate fraction comprising the detergent hydrocarbons and the heavy fraction is suitably done by distillation. Commercially available equipment can be used. The distillation may be carried out at atmospheric pressure, but also reduced pressure may be used. Preferably atmospheric pressure is used to remove the light fraction(s) and vacuum distillation is used to remove the heavy fraction.
The detergent hydrocarbons to be prepared according to the process of the invention are suitably C₁₀ to C₁₈ hydrocarbons, preferably C₁₀ to C₁₇ hydrocarbons, more preferably C₁₀ to C₁₃ hydrocarbons or more preferably C₁₄ to C₁₇ hydrocarbons. The use of C₁₀ to C₁₇ hydrocarbon, especially the C₁₀ to C₁₂ or the C₁₄ to C₁₇ hydrocarbons, result in the most suitable detergents.
The intermediate boiling fraction in the process of the present invention suitably comprises at least 80 wt% on total fraction of detergent hydrocarbons, preferably at least 90 wt%, more preferably at least 95 wt%, still more preferably at least 98 wt%. The detergent hydrocarbons consists mainly (i.e. at least 95 wt%) of paraffins (usually between 60 and 95 wt%), olefins (usually between 35 and 5 wt%) and oxygenates (usually mainly alcohols, between 0.1 and 5 wt%). The carbon skeleton of the paraffins, olefins and alcohols are identical, and usually contain between 2 and 20 wt%, more usually between 4 and 14 wt%, of branched carbon chains. Methyl groups, usually forming at least 80% of the branches, more usually at least 90%, are the main form of branches present.
Suitably the light fraction has a boiling range below 150 °C, preferably below 160 °C, more preferably below 170 °C. It is observed that one or more than one light boiling fractions may be removed from the hydrocarbonaceous Fischer-Tropsch stream. All these fractions suitably boil below the above mentioned temperatures. The light fraction may also boil at temperatures higher than mentioned above, but this will result in a loss of detergent hydrocarbons.
Suitably the heavy fraction has a boiling range starting at a temperature above 315 °C, preferably above 305 °C. It is observed that one or more than one heavy fraction may be removed from the hydrocarbonaceous Fischer-Tropsch stream, suitably all boiling above the temperature mentioned above. The heavy fraction may boil at a lower temperature than the ones mentioned above, but this will result in the loss of detergent hydrocarbons. In another embodiment of the invention the heavy fraction has a boiling range above 250 °C, preferably above 240 °C. In this way mainly C₁₀-C₁₃ detergent hydrocarbons are produced.
The intermediate fraction suitably has a boiling range from 170 °C to 315 °C, preferably between 170 °C and 240 °C (comprising mainly C₁₀-C₁₃ detergent hydrocarbons) or preferably between 250 °C and 315 °C (comprising mainly C₁₄-C₁₇ detergent hydrocarbons).
Very suitably the intermediate fraction comprises at least 80 wt%, preferably at least 90 wt%, more preferably at least 95 wt%, even more preferably at least 98 wt% based on total weight of the fraction, of detergent hydrocarbons in the range from C₁₀ to C₁₈ hydrocarbons, preferably C₁₀ to C₁₇ hydrocarbons, more preferably C₁₀ to C₁₃ hydrocarbons or more preferably C₁₄ to C₁₇ hydrocarbons.
The heavy fraction boiling above the intermediate fraction comprising the detergent hydrocarbons is preferably subjected to a hydrocracking process to convert any hydrocarbons present in the fraction boiling above the boiling point of middle distillates into hydrocarbons boiling in the middle distillates boiling range. During the hydrocracking step also hydroisomerisation will occur. In the hydrocracking/ hydroisomerisation step, hydrocarbon fuels are prepared from the hydrocarbon product of the one or more heavy Fischer-Tropsch fractions by hydrocracking and hydroisomerising the product with hydrogen in the presence of a suitable catalyst. Typically, the catalyst comprises as catalytically active component one or more metals selected from Groups VIB and VIII of the Periodic Table of Elements, in particular one or more metals selected from molybdenum, tungsten, cobalt, nickel, ruthenium, iridium, osmium, platinum and palladium. Preferably, the catalyst comprises one or more metals selected from nickel, platinum and palladium as the catalytically active component. Catalysts comprising platinum as the catalytically active component have been found to be particularly suitable for use in the second hydroconversion stage.
Catalysts for the hydrocracking step typically comprise a refractory metal oxide as a carrier. The carrier material may be amorphous or crystalline. Suitable carrier materials include silica, alumina, silica-alumina, zirconia, titania and mixtures thereof. The carrier may comprise one or more zeolites, either alone or in combination with one or more of the aforementioned carrier materials. Preferred carrier materials for inclusion in the catalyst for use in the process of this invention are silica, alumina and silica-alumina. A particularly preferred catalyst comprises platinum supported on an amorphous silica-alumina carrier.
As catalyst for the hydrocracking step a catalyst comprising zeolite beta may be used. In that case the catalyst preferably comprises 0.1-15 wt% of a zeolite beta, calculated on the weight of the catalyst. More preferably the zeolite beta in the catalyst is present in an amount of at least 0.5 wt%, more in particular in an amount of at least 1 wt%, and/or in an amount of at most 10 wt%, more in particular in an amount of at most 8 wt%, even more particular in an amount of at most 4 wt %, calculated on the weight of the catalyst.
The catalyst for the hydrocracking step may comprise 0.005 to 5.0 wt% of a Group VIII noble metal on a carrier, the carrier comprising 0.1-15 wt% of a zeolite beta and at least 40 wt% of an amorphous silica-alumina, calculated on the weight of the catalyst. Preferably such a catalyst comprises 0.005 to 5.0 wt% platinum and/or palladium. Preferably the zeolite beta in such a catalyst is present in an amount of at least 0.5 wt%, more in particular in an amount of at least 1 wt%, and/or in an amount of at most 10 wt%, more in particular in an amount of at most 8 wt%, even more particular in an amount of at most 4 wt %. The zeolite beta in the catalyst preferably has a silica:alumina molar ratio of at least 50, more preferably at least 75 and at most 500, calculated as SiO₂ and Al₂O₃. The amorphous silica-alumina preferably has an alumina content, calculated as Al₂O₃, of 5-70 wt%.
In the hydrocracking/hydroisomerisation stage of this process, the heavy Fischer-Tropsch hydrocarbon product is contacted with hydrogen in the presence of the catalyst at elevated temperature and pressure. Typically, the temperatures necessary to yield the hydrocarbon fuels will lie in the range of from 200 to 400 °C, preferably from 275 to 375 °C. The pressure typically applied ranges from 20 to 250 bars, more preferably from 40 to 200 bars. Hydrogen may be supplied at a gas hourly space velocity of from 100 to 10000 Nl/l/hr, preferably from 500 to 5000 Nl/l/hr. The hydrocarbon feed may be provided at a weight hourly space velocity of from 0.1 to 5 kg/l/hr, preferably from 0.25 to 2 kg/l/hr. The ratio of hydrogen to hydrocarbon feed may range from 100 to 5000 Nl/kg and is preferably from 250 to 2500 Nl/kg.
The degree of hydrocracking occurring in the hydrocracking/hydroisomerisation step may be measured by determining the degree of conversion of the fraction boiling above 370 °C. Typically, the hydrocracking/ hydroisomerisation stage is operated at a conversion of at least 40%.
The hydrocarbon fuel produced in the hydrocracking stage will typically comprise hydrocarbons having boiling points lying in a number of different fuel fractions, for example naphtha, kerosene and gasoil fractions. Separation of the hydrocarbon fuel into the appropriate fractions may be conveniently achieved using distillation techniques well known in the art.
In the process of the invention any reject streams obtained in the above described distillation processes may very suitably be used as additional feedstreams in the process for the preparation of fuels.
The detergent hydrocarbons, i.e. the molecules, especially paraffins and/or olefins, having the right number of carbon atoms, are converted into detergents according to methods known in the art. A very suitable method is the alkylation of aromatic compounds with olefins, followed by sulphonation and neutralization. The olefins may be the direct product of the Fischer-Tropsch reaction or obtained after dehydrogenation of paraffins. In the case that the intermediate fraction comprising the detergent hydrocarbons is obtained without any treatment, the olefins present in the fraction may be directly used for conversion into detergents. The remaining paraffins may be dehydrogenated, and the olefins thus obtained may be converted into detergents. Preferably the paraffins, directly obtained in the Fischer-Tropsch process, or obtained after hydrogenation of direct Fischer-Tropsch product, is at least partially catalytically dehydrogenated into mono-olefins before conversion into detergents.
In case the intermediate fraction comprising the detergent hydrocarbons is hydrogenated before distillation, any olefins or oxygenates are removed. This results in an optimum production of detergent hydrocarbons within a narrow carbon distribution range. Further, such hydrogenated fractions are more stable and less corrosive, making transport and/or storage easier.
In case the intermediate fraction obtained after distillation is hydrogenated before conversion into detergents, the hydrogenated fractions are more stable and less corrosive. This makes transport and/or storage easier. Hydrogenation after distillation avoids the need to hydrogenate a large amount of Fischer-Tropsch product.
The hydrogenation step suitably uses a catalyst comprising molybdenum, tungsten, cobalt, nickel, ruthenium, iridium, osmium, platinum or palladium as a catalytically active metal, preferably one or more of nickel and/or molybdenum, cobalt and/or tungsten, platinum and palladium. The hydrogenation step is suitably carried out at a temperature between 150 and 325 °C, preferably between 200 and 275 °C, a pressure between 5 and 120 bar, preferably between 20 and 70 bar. Hydrogen may be supplied to the hydroconversion stage at a gas hourly space velocity in the range of from 100 to 10000 Nl/l/hr, more preferably from 250 to 5000 Nl/l/hr. The hydrocarbon product being treated is typically supplied to the hydroconversion stage at a weight hourly space velocity in the range of from 0.1 to 5 kg/l/hr, more preferably from 0.25 to 2.5 kg/l/hr. The ratio of hydrogen to hydrocarbon product may range from 100 to 5000 Nl/kg and is preferably from 250 to 3000 Nl/kg.
Catalysts for use in the hydrogenation step typically comprise a refractory metal oxide or silicate as a carrier. Suitable carrier materials include silica, alumina, silica- alumina, zirconia, titania and mixtures thereof. Preferred carrier materials for inclusion in the catalyst for use in the process of this invention are silica, alumina and silica-alumina.
The catalyst may comprise the catalytically active component in an amount of from 0.05 to 80 parts by weight, preferably from 0.1 to 70 parts by weight, per 100 parts by weight of carrier material. The amount of catalytically active metal present in the catalyst will vary according to the specific metal concerned. One particularly suitable catalyst for use in the first hydroconversion stage comprises nickel in an amount in the range of from 5 to 70 parts by weight per 100 parts by weight of carrier material. A second particularly suitable catalyst comprises platinum in an amount in the range of from 0.05 to 2.0 parts by weight per 100 parts by weight of carrier material.
Suitable catalysts for use in the hydrogenation step of the process of this invention are available commercially, or may be prepared by methods well known in the art, for example the methods discussed hereinbefore with reference to the preparation of the hydrocarbon synthesis catalyst.
The hydrogenation step is operated under conditions such that substantially no isomerization or hydrocracking of the feed occurs. The precise operating conditions required to achieve the desired degree of hydrogenation without substantial hydrocracking or hydroisomerisation occurring will vary according to the composition of the hydrocarbon product being fed to the hydroconversion stage and the particular catalyst being employed. As a measure of the severity of the conditions prevailing in the hydroconversion stage and, hence, the degree of hydrocracking and isomerization occurring, the degree of conversion of the feed hydrocarbon may be determined. In this respect, conversion, in percent, is defined as the percent weight of the fraction of the feed boiling above 220 °C which is converted during the hydroconversion to a fraction boiling below 220 °C. The conversion of the hydroconversion stage is below 20%, preferably below 10%, more preferably below 5%. In the case that there is too much hydroisomerisation and/or hydrocracking a decrease of the temperature or the use of a catalyst with a less acidic catalyst function will usually solve the problem.
The desired detergent hydrocarbons are then suitably dehydrogenated. This may be done using processes well known in the art. For instance, the PACOL process of UOP optionally complemented by the DEFINE process of UOP (to convert any dienes in the feed to mono-olefins).
In general, dehydrogenation of the detergent hydrocarbons in the instant process can be accomplished using any of the well-known dehydrogenation catalyst systems or "conventional dehydrogenation catalysts" including those described in "Detergent Manufacture Including Zeolite Builders and Other New Materials", Ed. Sittig, Noyes Data Corp., New Jersey, 1979 and other dehydrogenation catalyst systems, for example those commercially available though UOP Corp. Dehydrogenation can be conducted in presence of hydrogen gas and commonly a precious metal catalyst is present though alternatively non-hydrogen, precious-metal free dehydrogenation systems such as a zeolite/air system can be used with no precious metals present.
As is well known, dehydrogenation can be complete or partial, more typically partial. Usually between 5 and 50 wt% olefins are formed, suitably between 5 and 20 wt%. When partial, this step forms a mixture of olefin and unreacted paraffin. Such mixture is a suitable feed for e.g. a benzene alkylation step. After work up of the alkylation step, the unconverted paraffins may be recirculated to the start of the dehydrogenation process.
Suitably the dehydrogenation process uses a catalyst containing molybdenum, tungsten, cobalt, nickel, ruthenium, iridium, osmium, platinum or palladium as a catalytically active metal, preferably one or more of nickel and/or molybdenum, cobalt and/or tungsten, platinum and palladium, more preferably platinum.
The dehydrogenation step is suitably carried out at a temperature between 300 and 600 °C, preferably between 400 and 500 °C, a pressure between 0.1 and 20 bar, preferably between 1 and 4 bar.
Following the dehydrogenation, the detergent hydrocarbon is converted into a detergent according to methods well known in the art. Suitably the reaction is selected from the following reactions:

alkylation with benzene or toluene optionally followed by sulfonation and neutralisation;
alkylation with phenol followed by at least one of alkoxylation, sulfonation and neutralisation, sulfation and neutralisation or alkoxylation combined with oxidation;
hydroformylation optionally followed by at least one of alkoxylation, glycosylation, sulfation, phosphatation or combinations thereof
sulfonation;
epoxidation;
hydrobromination followed by amination and oxidation to amine oxide; and
phosphonation.

A particularly preferred option is the alkylation of mono-aromatic compounds, e.g. benzene, toluene, xylene and mixtures thereof, followed by sulphonation. The alkylation process may use aluminium chloride, HF, fluoridated zeolites, non-acidic calcium mordenite and the like as catalyst. For example, appropriate process conditions for AlCl₃ alkylation are exemplified by a reaction of 5 mole% AlCl₃ relative to the detergent hydrocarbon at 100-300 °C for 0.5-1.0 hour in a batch or continuous reactor. Other suitable alkylation catalyst may be selected from shape-selective moderately acidic alkylation catalysts, preferably zeolitic. The zeolite in such catalysts for the alkylation step is preferably selected from the group consisting of mordenite, ZSM-4, ZSM-12, ZSM-20, offretite, gmelinite and zeolite beta in at least partially acidic form. More preferably, the zeolite in the alkylation step is substantially in acid form and is contained in a catalyst pellet comprising a conventional binder and further wherein said catalyst pellet comprises at least about 1%, more preferably at least 5%, more typically from 50% to about 90%, of said zeolite. A commercially available process is the DETAL process.
More generally, suitable alkylation catalyst is typically at least partially crystalline, more preferably substantially crystalline not including binders or other materials used to form catalyst pellets, aggregates or composites. Moreover the catalyst is typically at least partially acidic. H-form mordenite is a suitable catalyst.
In a preferred embodiment the detergent hydrocarbons are converted into highly linear alcohols according to the process as described in PCT/EP02/06373 .
Beside the above described processes for the preparation of detergents, also other, well known process may be used. For instance, the detergent hydrocarbons, especially a preferred range of C₁₄-C₁₇ detergent hydrocarbons, may be converted into detergents via chlorination or sulfonation of the hydrogenated C₁₄-C₁₇ stream. Also the preparation of detergents directly from paraffins as described in WO 99/59942 may be used.
In this specification the term "mainly" means at least 80 wt%, unless otherwise specified. When an amount of a product or mixture is indicated as "wt%", the percentage is based on the total product stream in which the product is present, unless otherwise specified. Under "normally liquid hydrocarbon product" is meant any product which is at STP (1 bar, 0 °C) a liquid product.
For saturated hydrocarbons this means C₅ ⁺ hydrocarbons. Under "normally solid product" is meant any product which is solid at STP. For saturated normal hydrocarbons this means C₁₅ ⁺. The term C_n ⁺ relates to molecules comprising n carbon atoms or more. The term C_n ^- refers to molecules comprising n carbon atoms or less. The term "middle distillates", as used herein, is a reference to hydrocarbon mixtures of which the boiling point range corresponds substantially to that of kerosene and diesel fractions obtained in a conventional atmospheric distillation of crude mineral oil.

Example

A cobalt containing Fischer-Tropsch catalyst (12 pbw Co on 100 pbw titania, Mn promoter) was tested at several conditions in the same reactor. The following results were obtained.

Pressure	60 bara	40 bara	30 bara	20 bara
Temperature	213 °C	215 °C	214 °C	215 °C
STY(space time yield), kg/m³/h	150	150	100	100
C₁₂ isoparaffin wt%, based on total C₁₂ product weight	2.7	5.1	8.9	>10

Claims

A process for the preparation of detergents containing a relatively low amount of isoparaffins, comprising:
- separating by distillation the hydrocarbonaceous product stream from a Fischer-Tropsch process carried out using a cobalt based catalyst and a pressure above 25 bara into
• a light fraction (A) boiling below a first intermediate fraction (Bⁱ),

• a first intermediate fraction (Bⁱ) comprising at least 80 wt% C₁₀ to C₁₄ hydrocarbons based on the total first intermediate fraction (Bⁱ),

• a second intermediate fraction (Bⁱⁱ) comprising at least 80 wt% C₁₄ to C₁₈ hydrocarbons based on the total second intermediate fraction (Bⁱⁱ), and

• a heavy fraction (C) boiling above the second intermediate fraction (Bⁱⁱ),

- hydrogenating the fraction (Bⁱ) and hydrogenating the fraction (Bⁱⁱ),

- separating the hydrogenated first intermediate fraction by distillation into
• a fraction (Bⁱ¹) comprising at least 80 wt% C₁₀ to C₁₃ hydrocarbons based on the total fraction (Bⁱ¹)

• a fraction (Bⁱ²) comprising at least 80 wt% C14 hydrocarbons based on the total fraction (Bⁱ²),

- separating the hydrogenated second intermediate fraction by distillation into
• a fraction (Bⁱⁱ¹) comprising at least 80 wt% C₁₄ to C₁₇ hydrocarbons based on the total fraction (Bⁱⁱ¹)
and

• a fraction (Bⁱⁱ²) comprising at least 80 wt% C₁₈ hydrocarbons based on the total fraction (Bⁱⁱ²)

- optionally adding the fraction (Bⁱ²) to the fraction (Bⁱⁱ¹)

- converting the C₁₀ to C₁₃ hydrocarbons in the fraction (Bⁱ¹) into detergents, and/or converting the C₁₄ to C₁₇ hydrocarbons in the fraction (Bⁱⁱ¹), or in (Bⁱⁱ¹) plus (Bⁱ²), into detergents, and

- optionally subjecting at least a part of the fraction (Bⁱⁱ²) to hydrocracking.
A process according to claim 1, wherein the fraction (Bⁱ²) is added to the fraction (Bⁱⁱ¹).
A process according to claim 2, wherein the C₁₄ to C₁₇ hydrocarbons in (Bⁱⁱ¹) plus (Bⁱ²) are converted into detergents.
A process according to any one of the preceding claims, wherein the light fraction (A) has a boiling range below 150 °C, preferably below 160 °C, more preferably below 170 °C, and/or in which the heavy fraction (C) has a boiling range above 315 °C, preferably above 305 °C, preferably in which the heavy fraction (C) has a boiling range above 250 °C, preferably above 240 °C.
A process according to any one of the preceding claims, wherein the heavy fraction (C) is subjected to a hydrocracking process to convert any hydrocarbons present in the fraction boiling above the boiling point of middle distillates into hydrocarbons boiling in the middle distillates boiling range.
A process according to any one of the preceding claims, wherein the Fischer-Tropsch process is carried out at a pressure above 35 bara.
A process according to any one of the preceding claims, wherein the Fischer-Tropsch process is a low temperature process, preferably carried out at a temperature between 180 and 270 °C, more preferably between 200 and 250 °C.
A process according to any one of the preceding claims, wherein the first intermediate fraction (Bⁱ) comprises at least 90 wt%, preferably at least 95 wt%, more preferably at least 98 wt% C₁₀ to C₁₄ hydrocarbons based on the total first intermediate fraction (Bⁱ).
A process according to any one of the preceding claims, wherein the second intermediate fraction (Bⁱⁱ) comprises at least 90 wt%, preferably at least 95 wt%, more preferably at least 98 wt% C₁₄ to C₁₈ hydrocarbons based on the total second intermediate fraction (Bⁱⁱ).
A process according to any one of the preceding claims, wherein fraction (Bⁱ) fraction (Bⁱⁱ) the hydrogenated using a catalyst comprising molybdenum, tungsten, cobalt, nickel, ruthenium, iridium, osmium, platinum or palladium as a catalytically active metal, preferably one or more of nickel and/or molybdenum, cobalt and/or tungsten, platinum and palladium, preferably at a temperature between 150 and 325 °C, more preferably between 200 and 275 °C, and preferably at a pressure between 5 and 120 bar, more preferably between 20 and 70 bar.
A process according to any one of the preceding claims, wherein the C₁₀ to C₁₃ hydrocarbons and/or the C₁₄ to C₁₇ hydrocarbons are at least partially catalytically dehydrogenated into mono-olefins before conversion into detergents.
A process according to any one of the preceding claims, wherein the conversion of the C₁₀ to C₁₃ hydrocarbons and/or the C₁₄ to C₁₇ hydrocarbons, optionally after dehydrogenation, into detergents comprises at least one step selected from:
- alkylation with benzene or toluene optionally followed by sulfonation and neutralisation;

- alkylation with phenol followed by at least one of alkoxylation, sulfonation and neutralisation, sulfation and neutralisation or alkoxylation combined with oxidation;

- hydroformylation optionally followed by at least one of alkoxylation, glycosylation, sulfation, phosphatation or combinations thereof

- sulfonation;

- epoxidation;

- hydrobromination followed by amination and oxidation to amine oxide; and phosphonation.